The primary objective of this project is to investigate variables which promote inhibit independent exploration of the environment by nonambulatory, profoundly retarded multiply handicapped individuals in an institutional setting. In longitudinal studies and experimental manipulations, we will examine the nature of exploratory behavior as exhibited in the living environment, and investigate both environmental (e.g., characteristics of stimulus materials) and client (e.g., handicapped conditions) variables which may affect the level and type of exploratory behavior exhibited. Based on the information from these studies, interventions will be designed and implemented in an attempt to improve the level and quality of exploratory behavior exhibited in the environment. The efficacy and these interventions will be empirically examined. Based on previous research, levels of exploratory behavior are expected to increase fivefold as a result of the interventions. Clients presently engage in an average of five hrs of exploratory behavior per week; this is expected to increase to an average of 25 or more hrs/week once the intervention phase is begun. A change of this magnitude should have a dramatic and long-term impact on the rate of development for these individuals. Using a control-group comparison, the actual effects on development of maintained improvements in exploratory behavior will be examined over a one yr period. During this period, experimental subjects may engage in an average of 1300 hrs of exploratory behavior, compared to an average of only 260 hrs (based on existing levels) for control subjects. This difference should result in significant improvements for experimental subjects in responsiveness to the environment, physical conditioning (e.g., muscle strength), and cognitive and sensorimotor development. Documentation of these gains will validate the importance of exploratory behavior to development for this population. This research will have important implications for the modification and future design of living environments for the profoundly multi-handicapped, suggesting methods of structuring a supportive environment which will be conductive to all aspects of development. The information derived from this research will lead toward a taxonomy of exploratory behavior by physical handicap, useful in selecting effective interventions.